Zhang Xiao-Hong, Saeed Tareq, Algehyne Ebrahem A, El-Shorbagy M A, El-Refaey Adel M, Ibrahim Muhammad
College of Science, Hunan City University, Yiyang, 413000, People's Republic of China.
Nonlinear Analysis and Applied Mathematics (NAAM)-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.
Sci Rep. 2021 Aug 12;11(1):16458. doi: 10.1038/s41598-021-95803-z.
In this paper, the natural convection heat transfer of water/alumina nanofluid is investigated in a closed square cavity. An oblique magnetic field is applied on the cavity of angle [Formula: see text]. There is also radiation heat transfer in the cavity. The cavity includes a high-temperature source of L-shape. A low-temperature source as a quadrant of a circle is placed at the corner of the cavity. All other walls are well insulated. The novelty of this work is a low-temperature obstacle embedded in the cavity. Simulations are conducted with a Fortran code based on the control volume method and simple algorithm. Entropy generation rate, Bejan number, and heat transfer are studied by changing different parameters. Results indicate that the highest rates of heat transfer and entropy generation have occurred for the perpendicular magnetic field at high values of the Rayleigh number. At these Rayleigh numbers, the minimum value of the Bejan number is obtained for 15° magnetic field. The magnetic field variation can lead to a change up to 53% in Nusselt number and up to 34% in generated entropy. In a weak magnetic field, the involvement of the radiation heat transfer mechanism leads to an increase in the heat transfer rate so that the Nusselt number can be increased by ten units considering the radiation heat transfer when there is no magnetic field. The maximum heat transfer rate occurs in the horizontal cavity and the minimum value in the cavity of 60° angle. For water, these values are 10.75 and 9.98 for 0 and 60 angles, respectively. Moreover, a weak magnetic field increases the heat transfer rate in the absence of the radiation mechanism, while it is reduced by considering a strong magnetic field.
本文研究了封闭方腔内水/氧化铝纳米流体的自然对流换热。在腔上施加了一个倾斜角为[公式：见原文]的磁场。腔内还存在辐射换热。腔体内有一个L形高温源。在腔体角落处放置了一个呈四分之一圆的低温源。所有其他壁面均良好隔热。这项工作的新颖之处在于腔体内嵌入了一个低温障碍物。基于控制体积法和简单算法，用Fortran代码进行了模拟。通过改变不同参数研究了熵产生率、贝扬数和传热情况。结果表明，在瑞利数较高时，垂直磁场下的传热和熵产生率最高。在这些瑞利数下，15°磁场时贝扬数取得最小值。磁场变化可使努塞尔数变化高达53%，产生的熵变化高达34%。在弱磁场中，辐射换热机制的参与导致传热率增加，以至于在无磁场时考虑辐射换热，努塞尔数可增加十个单位。最大传热率出现在水平腔体内，最小值出现在60°角的腔体内。对于水，0°和60°角时这些值分别为10.75和9.98。此外，在没有辐射机制的情况下，弱磁场会提高传热率，而考虑强磁场时传热率会降低。
